Password Encrypter

def program():
    def validation(inp):
        split = inp.split(" ")
        if len(split)==2 and (split[0].lower()=="enc" or split[0].lower()=="dec"):
            return True, split[0].lower(), split[1]
        else:
            return False, "",""
    encryption_syntax = [
        ['a','∞'],
        ['A','8'],
        ['b','`'],
        ['B','{'],
        ['c','/'],
        ['C','('],
        ['d','+'],
        ['D',')'],
        ['e','c'],
        ['E','3'],
        ['f','?'],
        ['F','#'],
        ['g','}'],
        ['G','$'],
        ['h','O'],
        ['H',';'],
        ['i','-'],
        ['I','|'],
        ['j','B'],
        ['J','['],
        ['k','z'],
        ['K','@'],
        ['l','.'],
        ['L','1'],
        ['m','5'],
        ['M','='],
        ['n','<'],
        ['N','A'],
        ['O','0'],
        ['o','*'],
        ['p','%'],
        ['P',']'],
        ['q','Y'],
        ['Q','F'],
        ['r','>'],
        ['R','\\'],#double slash cause its an escape char
        ['s','~'],
        ['S','^'],
        ['t','M'],
        ['T','f'],
        ['u','!'],
        ['U',','],
        ['v','"'],
        ['V','p'],
        ['w','v'],
        ['W','V'],
        ['x',':'],
        ['X',';'],
        ['y','7'],
        ['Y','a'],
        ['z','j'],
        ['Z','9'],
        ['3','i'],
        ['9','&']
                         ]

    inp=input()

    passed, keyword, password = validation(inp)

    if passed:
        def convert(num,num2):
            new_password=""
            i = 0
            for char in password:
                for char_set in encryption_syntax:
                    if char==char_set[num]:
                        new_password+=char_set[num2]
                        break;
                i+=1
            return new_password
        if keyword == "enc":
            print(convert(0,1))
        if keyword == "dec":
            print(convert(1,0))
    else:
        print("Invalid Input")
    program()
program()